L2C and Next-Generation Smart PNT Receivers

August 12, 2015By
SVN49 in space  (artist’s rendering).  The signal anomaly from SVN 49 alerted researchers to new possibilities in analysis and monitoring.

Are you using a legacy-model PNT (position, navigation and timing) receiver or a smart PNT receiver, and why does it matter? Don’t have a clue? Read on! Hint — L2C and CNAV (civilian navigation message format) are the major reason it matters. Yes, it’s all because of L2C, the controversial GPS civilian signal that seems to always be in the news and just... read more

To L2C or Not to L2C? That Is the Operational Question.

July 22, 2015By

Half of the GPS constellation now transmits the new civil signal, L2C. In a matter of weeks, that number will crest into the majority of the constellation when IIF-10 is set active and operational to users. By the end of the year or early 2016, look for 18 usable satellites transmitting L2C. That could be considered a nominal initial operating... read more

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Activation of Pre-Operational CNAV Message Set for April 28

April 24, 2014By

U.S. Air Force Space Command will be implementing CNAV messages on the GPS L2C and L5 signals beginning April 28 at 14:30 UTC, to facilitate user familiarization and development of compatible user equipment. No GPS satellite outages or degradations are planned. The L2C and L5 CNAV messages should be transparent to users. A 30-day public comment period on the pre-operational CNAV... read more

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PNT Advisory Board Hears Air Force CNAV Plan

March 12, 2014By

The U.S. National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board has published the minutes of its December 4–5, 2013, meeting, opening with a quote from Albert Einstein, “We cannot solve our problems with the same thinking we used when we created them,” courtesy of Board Chair Dr. James Schlesinger. Among many other topics addressed, the Board heard a report... read more

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Comment Period on Pre-Operational CNAV Message Opens

March 5, 2014By
Carrier-to-noise ratio of L5 signals, measured on June 19, 2013, by  Zheng Yao and colleagues at Tsinghua University, China. Signals were analyzed from three GPS satellites whose PRN numbers are 1, 24, 25, and one QZSS satellites with the PRN of 193 at time of acquisition.

A Federal Register Notice has been published allowing for a 30-day comment period on the proposed CNAV message on L2C and L5. The notice seeks comment from the public and industry regarding plans by the U.S. Air Force to broadcast pre-operational L2C and L5 civil  navigation (CNAV) messages from certain GPS satellites beginning in April. The Department of Transportation is... read more

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Air Force Directs Early Civil Navigation (CNAV) Message-Populated L2C and L5 Signals

December 17, 2013By

The U.S. Air Force is directing transmission of continuous CNAV message-populated L2C and L5 signals starting in April 2014. The move is designed to help development of user equipment compatible with the civil signals. Full text of the CNAV memo appears below. MEMORANDUM FOR THE NATIONAL COORDINATION OFFICE FOR SPACE BASED POSITIONING, NAVIGATION AND TIMING ATTENTION: DR. JAN BRECHT-CLARK FROM:... read more

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2C or Not 2C: The First Live Broadcast of GPS CNAV Messages

July 8, 2013By

By Oliver Montenbruck, Richard B. Langley, and Peter Steigenberger Over the past several years, some users of the GPS navigation system have already benefitted from the addition of various new signals in addition to the legacy C/A- and P(Y)-code. With the introduction of the Block IIR-M satellites in 2005, a new civil signal (L2C) was transmitted on the L2 frequency,... read more

GPS CNAV Civil Capabilities Now Being Tested

June 17, 2013By

U.S. Air Force Space Command is now testing CNAV capabilities on the GPS L2 and L5 signals. The initial CNAV Live-Sky Broadcast began June 15 and will take place until June 29. Civil users and manufacturers are invited to participate. The GPS Directorate (SMC/GP) is implementing the CNAV (Civil Navigation) Test Program, conducting Live-Sky CNAV testing before deployment of the... read more

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